Cataract extraction is one of the most commonly performed surgical procedures in the world with estimated 2.5 million cases performed annually in the United States and 9.1 million cases worldwide in 2000. This was expected to increase to approximately 13.3 million estimated global cases in 2006. This market is composed of various segments including intraocular lenses for implantation, viscoelastic polymers to facilitate surgical maneuvers, disposable instrumentation including ultrasonic phacoemulsification tips, tubing, and various knives and forceps. Modern cataract surgery is typically performed using a technique termed phacoemulsification in which an ultrasonic tip with an associated water stream for cooling purposes is used to sculpt the relatively hard nucleus of the lens after performance of an opening in the anterior lens capsule termed anterior capsulotomy or more recently capsulorhexis. Following these steps as well as removal of residual softer lens cortex by aspiration methods without fragmentation, a synthetic foldable intraocular lens (IOL) is inserted into the eye through a small incision.
One of the earliest and most critical steps in the procedure is the performance of capsulorhexis. This step evolved from an earlier technique termed can-opener capsulotomy in which a sharp needle was used to perforate the anterior lens capsule in a circular fashion followed by the removal of a circular fragment of lens capsule typically in the range of 5-8 mm in diameter. This facilitated the next step of nuclear sculpting by phacoemulsification. Due to a variety of complications associated with the initial can-opener technique, attempts were made by leading experts in the field to develop a better technique for removal of the anterior lens capsule preceding the emulsification step. The concept of the Continuous Curvilinear Capsulorhexis (CCC) is to provide a smooth continuous circular opening through which not only the phacoemulsification of the nucleus can be performed safely and easily, but also for easy insertion of the intraocular lens. It provides both a clear central access for insertion, a permanent aperture for transmission of the image to the retina by the patient, and also a support of the IOL inside the remaining capsule that would limit the potential for dislocation. Subsequent to the step of anterior CCC, and prior to IOL insertion the steps of hydrodissection, hydrodilineation and phaco emulsification occur. These are intended to identify and soften the nucleus for the purposes of removal from the eye. These are the longest and thought to be the most dangerous step in the procedure due to the mechanical manipulation and the use of pulses of ultrasound that may lead to inadvertent ruptures of the posterior lens capsule, posterior dislocation of lens fragments, and potential damage anteriorly to the conical endothelium and/or iris and other delicate intraocular structures. The central nucleus of the lens, which undergoes the most opacification and thereby the most visual impairment, is structurally the hardest and requires special techniques. A variety of surgical maneuvers employing ultrasonic fragmentation and also requiring considerable technical dexterity on the part of the surgeon have evolved, including sculpting, cracking and chopping of the lens, the so-called “divide and conquer technique” and a whole host of similarly creatively named techniques, such as phaco chop, etc. These are all subject to the usual complications associated with delicate intraocular maneuvers.
What is needed are ophthalmic methods, techniques and apparatus to advance the standard of care of cataract and other ophthalmic pathologies.